How do I get email notification working

I have been given the job of database administrator. I very good at SQL
programming, but am just learning about things like backups, replication,
etc. and am VERY shaky on anything involving network administration. I am
not the one who installed Sql 2005 database, so I don't know if any steps
were missed.
Email notification does not work, and I don't know if it ever did. I have
to remember to run a CheckJobs script periodically because the system is not
going to tell me if something goes wrong.
I would like to get this working, but I don't know where to start. The
70-431 Training Kit says that Database Mail must be enabled through the SQL
Server Surface Area Configuration tool, but when I open that up, I have no
idea what I'm supposed to day.
I also went through the Database Mail Configuration Wizard; no error
messages but also no messages coming through my email. When I view the
history, I see a lot of failures, but nothing that tells me why.
How do I fix this?